OFFSET
1,4
COMMENTS
An unlabeled rooted tree has strictly thinning limbs if its outdegrees are strictly decreasing from root to leaves.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..300
EXAMPLE
The a(7) = 7 trees: (oo(o(o))), (o(o)(oo)), (ooo(oo)), ((o)(o)(o)), (oo(o)(o)), (oooo(o)), (oooooo).
MATHEMATICA
stinctQ[t_]:=And@@Cases[t, b_List:>Length[b]>Max@@Length/@b, {0, Infinity}];
strut[n_]:=strut[n]=If[n===1, {{}}, Select[Join@@Function[c, Union[Sort/@Tuples[strut/@c]]]/@IntegerPartitions[n-1], stinctQ]];
Table[Length[strut[n]], {n, 20}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 16 2018
EXTENSIONS
a(26)-a(40) from Alois P. Heinz, Jan 17 2018
STATUS
approved